Phenyl dimethyl end-capped or triphenyl end-capped methylphenyl silicone oil and preparation method thereof

Abstract

The present invention relates to a phenyl dimethyl end-capped or triphenyl end-capped methylphenyl silicone oil and a preparation method thereof. The methylphenyl silicone oil of the present invention comprises: (i) an end-capping group represented by formula (1) or formula (2), (ii) a structural unit represented by formula (3), and (iii) one or two structural units selected from the structural units represented by formula (4) and formula (5). The methylphenyl silicone oil of the present invention has the advantages of high refractive index, suitable viscosity, high flash point, high transparency, and excellent heat resistance, aging resistance and radiation resistance, and can be easily prepared by a simple and safe method. Formula (1), formula (2), formula (3), formula (4), formula (5).

Description

Technical Field

[0001] The invention belongs to the field of polymer materials, and in particular relates to phenyl dimethyl end-capped or triphenyl end-capped methyl phenyl silicone oil and a preparation method thereof. Background Art

[0002] Methyl phenyl silicone oil is generally referred to as silicone oil in which some of the methyl groups on methyl silicone oil are replaced by phenyl groups. Due to its excellent high and low temperature resistance, good lubrication performance, radiation resistance and better compatibility with materials such as plastics and rubber, phenyl silicone oil is widely used in lubrication, insulation, demoulding, damping, shockproof and dustproof fields. There are no special requirements for the end-capping of methyl phenyl silicone oil, which currently mainly includes trimethyl end-capped methyl phenyl silicone oil and methyl diphenyl end-capped methyl phenyl silicone oil.

[0003] Trimethyl-terminated methylphenyl silicone oil is mainly prepared by polymerization of trimethylchlorosilane, hexamethyldisiloxane or methyl silicone oil as end caps. The advantage of pure methyl end caps is that the raw materials are easily available and the price is relatively cheap, so the market share is relatively high.

[0004] The capping agent of methyldiphenyl terminated phenyl silicone oil is prepared by hydrolysis, telomerization and other processes of methyldiphenylalkoxysilane prepared by methylalkoxysilane and chlorobenzene in the presence of metallic sodium. The advantage of methyldiphenyl terminated methylphenyl silicone oil is better heat resistance, which is more advantageous for preparing methylphenyl silicone oil with high refractive index and low viscosity.

[0005] At present, the method for synthesizing phenyl silicone oil mainly includes two methods: equilibrium method and hydrolysis condensation method. The equilibrium method uses phenyl siloxane ring body and methyl siloxane ring body as raw materials and is prepared by equilibrium polymerization reaction. For example: Patent document 1 discloses a method for preparing phenyl methyl silicone oil, which uses octamethyl cyclotetrasiloxane, methyl phenyl cyclotrisiloxane, dimethyl tetraphenyl disiloxane, tetramethyl ammonium hydroxide, polyethylene oxide, hexamethyl disiloxane, and o-benzoyl sulfonyl imide as raw materials to prepare phenyl methyl silicone oil. Patent document 2 discloses a method for preparing phenyl methyl silicone oil, which uses dimethyl diphenyl mixed cyclosiloxane, octamethyl cyclotetrasiloxane, tetramethyl ammonium hydroxide silicon alkoxide, and hexamethyl disiloxane as raw materials to prepare phenyl methyl silicone oil.

[0006] References:

[0007] Patent document 1: CN106977720A;

[0008] Patent document 2: CN107759790A. Summary of the invention

[0009] For trimethyl terminated methylphenyl silicone oil, its preparation has relatively high requirements for the phenyl ring body, and the introduction of too many methyl groups will make it difficult to obtain silicone oil with high refractive index and low viscosity.

[0010] For methyldiphenyl terminated phenyl silicone oil, the disadvantages of the phenyl capping agent are that the preparation process has great safety risks and purification is relatively difficult. Most of the domestically produced methyldiphenyl terminated silicone oils are used to prepare methylphenyl silicone oil without purification, and this phenyl capping agent has a high boiling point and is difficult to remove from the system, so it will have an adverse effect on the performance of methylphenyl silicone oil.

[0011] The technical problem to be solved by the present invention is to provide a methylphenyl silicone oil which has high refractive index, suitable viscosity, high flash point, high transparency, excellent heat resistance, aging resistance and radiation resistance, and can be easily prepared by a simple and safe method.

[0012] In view of the problems in the prior art, the present invention provides a phenyl dimethyl end-capped or triphenyl end-capped methylphenyl silicone oil and a preparation method thereof.

[0013] Specifically, the present invention solves the problem of the present invention through the following solutions.

[0014] [1] A methylphenyl silicone oil comprising:

[0015] (i) a blocking group represented by formula (1) or formula (2),

[0016] (ii) a structural unit represented by formula (3), and

[0017] (iii) one or two structural units selected from the structural units represented by formula (4) and formula (5),

[0018] Formula (1), Formula (2),

[0019] Formula (3),

[0020] Formula (4), Formula (5).

[0021] [2] The methylphenyl silicone oil according to [1], wherein, based on the total molar number of the structural units represented by formula (3), formula (4) and formula (5), the content of the structural unit represented by formula (3) is 15 to 100 mol%, the content of the structural unit represented by formula (4) is 0 to 85 mol%, and the content of the structural unit represented by formula (5) is 0 to 45 mol%.

[0022] [3] The methylphenyl silicone oil according to [1] or [2], wherein the methylphenyl silicone oil has a structure represented by the following formula (I) or (II):

[0023] Formula (I),

[0024] Formula (II),

[0025] Wherein, x, y and z represent the molar ratio of the three structural units, x+y+z=1, x is 0.15~1, y is 0~0.85, and z is 0~0.45.

[0026] [4] The method for preparing methylphenyl silicone oil according to any one of [1] to [3], comprising the following steps:

[0027] (a) Dehydration: Dehydrating a mixture comprising dimethylcyclosiloxane, phenylcyclosiloxane, a capping agent and a catalyst,

[0028] (b) Equilibrium polymerization: the dehydrated mixture is subjected to polymerization reaction.

[0029] (c) Catalyst destruction: adding an acidic neutralizing agent to destroy the activity of the catalyst, and

[0030] (d) Removal of low boiling point substances from the reaction system;

[0031] Wherein, the phenylcyclosiloxane is one or more selected from octaphenylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, a mixed ring of methylphenyl and diphenyl, and their hydrolyzed oils;

[0032] The end-capping agent is diphenyltetramethyldisiloxane or hexaphenyldisiloxane;

[0033] The catalyst is potassium hydroxide;

[0034] The acidic neutralizer is at least one selected from phosphoric acid, silicon-based phosphate ester, acetic acid, and carbon dioxide.

[0035] [5] The preparation method according to [4], wherein the dehydration in step (a) is carried out by one or a combination of vacuum distillation or nitrogen bubbling; wherein the temperature during the vacuum distillation is 40 to 90°C, and the relative vacuum degree is -0.08 MPa to -0.1 MPa; and the mass amount of the end-capping agent is 5 to 20% relative to the total mass of the dimethylcyclosiloxane and the phenylcyclosiloxane.

[0036] [6] The preparation method according to [4], wherein in step (b), the polymerization reaction temperature is 150-190°C; and the amount of the catalyst used, calculated as potassium, is 20-200 ppm relative to the total weight of the reaction system.

[0037] [7] The preparation method according to [4], wherein in step (c), the reaction system is first cooled to 100-130°C, and then the acidic neutralizing agent is added to the reaction system; the amount of the acidic neutralizing agent added is 5-20 times the amount of the catalyst by mass.

[0038] [8] The preparation method according to [4], wherein in step (d), the low boiling point substances in the reaction system are removed by vacuum distillation or short-path distillation, the pressure of the vacuum distillation is below 100 Pa, and the temperature is 150-300°C; the low boiling point substances are one or more selected from diphenyltetramethyldisiloxane, dimethylcyclosiloxane, and methylphenylcyclosiloxane.

[0039] [9] The method according to [4], further comprising the step of preparing diphenyltetramethyldisiloxane or hexaphenyldisiloxane as a capping agent,

[0040] The step of preparing diphenyltetramethyldisiloxane comprises: hydrolyzing phenyldimethyl monochlorosilane in an organic solvent A in the presence of water, and then separating and purifying the reaction product; the separation and purification comprises separating the system after the hydrolysis reaction into layers, and then washing the organic layer with water, neutralizing with alkali, dehydrating, removing the solvent, and performing reduced pressure distillation operations;

[0041] The steps of preparing hexaphenyldisiloxane include: dissolving triphenylsilanol in an organic solvent B, then carrying out a condensation reaction in the presence of an alkali catalyst under the condition of solvent reflux, and then separating and purifying the reaction product; the separation and purification includes cooling crystallization, filtering, washing with water and drying.

[0042]

[10] The preparation method according to [9], wherein

[0043] The organic solvent A is a non-polar organic solvent; the organic solvent B is a polar organic solvent;

[0044] The base used for the alkaline neutralization and the alkaline catalyst are respectively one or more selected from organic bases and inorganic bases.

[0045] The methylphenyl silicone oil of phenyl dimethyl end-capping of the present invention can adopt diphenyltetramethyldisiloxane as end-capping agent preparation, and has well solved the problems existing in the preparation of high refractive index and low viscosity methylphenyl silicone oil. The boiling point of diphenyltetramethyldisiloxane is low, which is convenient to remove the low-boiling point substances in the methylphenyl silicone oil prepared to improve its flash point. And the raw material for the preparation of diphenyltetramethyldisiloxane can be prepared by methods such as Grignard method, sodium method, disproportionation method, the boiling point of the raw material is low, and it is liquid, so it can be rectified and purified, which causes the methylphenyl silicone oil finally obtained to be more superior in terms of heat resistance, flash point, transparency, molecular weight distribution, etc.

[0046] The triphenyl-terminated methylphenyl silicone oil of the present invention can adopt hexaphenyldisiloxane as end-capping agent preparation, and because the number of phenyl groups in the end-capping group is large, it also has better heat resistance, aging resistance and radiation resistance while having the advantages of high refractive index and suitable viscosity. Along with the continuous change of market, technology, output, the main raw material triphenylchlorosilane and triphenylsilanol for preparing hexaphenyldisiloxane are very easy to obtain, and the price is also relatively cheap. Although hexaphenyldisiloxane has a larger steric hindrance, owing to having three electron-withdrawing groups, it can be polymerized with methyl ring body or phenyl ring body and carry out equilibrium reaction under base catalysis. Hexaphenyldisiloxane has a larger viscosity coefficient for methylphenyl silicone oil, so it is more suitable for preparing silicone oil above medium viscosity. DETAILED DESCRIPTION

[0047] The following is a detailed description of the present invention. The technical features described below are described based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples.

[0048] <Terms and Definitions>

[0049] In this specification, "methylphenyl silicone oil" means methylphenyl polysiloxane.

[0050] In this specification, "room temperature" refers to a temperature range of 20 to 30°C, for example, 25°C.

[0051] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoint numerical values ​​A and B.

[0052] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0053] In this specification, the word "may" includes both performing a certain process and not performing a certain process.

[0054] In this specification, the use of "optionally" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0055] In this specification, the unit names used are all international standard unit names, and unless otherwise stated, the "%" used indicates weight or mass percentage.

[0056] In this specification, the references to "preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0057] <Methylphenyl silicone oil>

[0058] An object of the present invention is to provide a methylphenyl silicone oil comprising:

[0059] (i) a blocking group represented by formula (1) or formula (2),

[0060] (ii) a structural unit represented by formula (3), and

[0061] (iii) one or two structural units selected from the structural units represented by formula (4) and formula (5),

[0062] Formula (1), Formula (2),

[0063] Formula (3),

[0064] Formula (4), Formula (5).

[0065] The structural units represented by formula (1) and formula (2) are end-capping groups, which are derived from the end-capping agent used in the preparation process. Specifically, the phenyldimethylsilyl end-capping group represented by formula (1) can be derived from diphenyltetramethyldisiloxane as an end-capping agent, and the triphenylsilyl end-capping group represented by formula (2) can be derived from hexaphenyldisiloxane as an end-capping agent.

[0066] The structural units represented by formula (3), formula (4) and formula (5) are repeating units constituting the molecular chain of methylphenyl silicone oil. Among them, the dimethylsiloxy structural unit represented by formula (3) is an essential structural unit, and its proportion in the total structural units is 15 to 100 mol%, preferably 20 to 90 mol%, and more preferably 30 to 85 mol%, for example, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, and 80 mol%.

[0067] The structural units represented by formula (4) and formula (5) are structural units having a phenyl group. The methylphenyl silicone oil of the present invention may have only one of the structural units represented by formula (4) and formula (5), or may have the structural units represented by formula (4) and formula (5) at the same time. The proportion of the phenylmethylsiloxy structural unit represented by formula (4) in the total structural units is 0 to 85 mol%, preferably 10 to 80 mol%, more preferably 20 to 70 mol%, such as 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, and 65 mol%. The proportion of the diphenylsiloxane structural unit represented by formula (5) in the total structural units is 0 to 45 mol%, preferably 5 to 40 mol%, more preferably 10 to 35 mol%, such as 15 mol%, 20 mol%, 25 mol%, and 30 mol%.

[0068] In one embodiment, the present invention provides a phenyldimethyl terminated methylphenyl silicone oil having a structure shown in the following formula (I):

[0069] Formula (I),

[0070] Wherein, x, y and z represent the molar ratio of the three structural units and satisfy x+y+z=1; wherein x is 0.15~1, preferably 0.2~0.9, more preferably 0.3~0.85; y is 0~0.85, preferably 0.1~0.8, more preferably 0.2~0.7; z is 0~0.45, preferably 0.05~0.4, more preferably 0.1~0.35.

[0071] For example, x may be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, etc.; y may be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, etc.; z may be 0.15, 0.2, 0.25, 0.3, etc.

[0072] The phenyl dimethyl terminated methylphenyl silicone oil of the present invention has the characteristics of high refractive index, low viscosity, high flash point, high transparency and excellent heat resistance, aging resistance and radiation resistance.

[0073] In another embodiment, the present invention provides a triphenyl-terminated methylphenyl silicone oil having a structure shown in the following formula (II):

[0074] Formula (II),

[0075] Wherein, x, y and z represent the molar ratio of the three structural units and satisfy x+y+z=1; wherein x is 0.15~1, preferably 0.2~0.9, more preferably 0.3~0.85; y is 0~0.85, preferably 0.1~0.8, more preferably 0.2~0.7; z is 0~0.45, preferably 0.05~0.4, more preferably 0.1~0.35.

[0076] For example, x may be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, etc.; y may be 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, etc.; z may be 0.15, 0.2, 0.25, 0.3, etc.

[0077] The triphenyl terminated methylphenyl silicone oil of the present invention has the characteristics of high refractive index, medium viscosity, high flash point, high transparency and excellent heat resistance, aging resistance and radiation resistance.

[0078] <Preparation method>

[0079] An object of the present invention is to provide a method for preparing the methylphenyl silicone oil of the present invention, characterized in that it comprises the following steps:

[0080] (a) Dehydration: Dehydrating a mixture comprising dimethylcyclosiloxane, phenylcyclosiloxane, a capping agent and a catalyst,

[0081] (b) Equilibrium polymerization: the dehydrated mixture is subjected to polymerization reaction.

[0082] (c) Catalyst destruction: adding an acidic neutralizing agent to destroy the activity of the catalyst, and

[0083] (d) Removal of low boiling point substances from the reaction system.

[0084] In one embodiment, the preparation method of the present invention further comprises the step of preparing diphenyltetramethyldisiloxane or hexaphenyldisiloxane as a capping agent.

[0085] The raw materials and each step of the preparation method of the present invention are described in detail below.

[0086] Raw materials and dosage

[0087] The dimethylcyclosiloxane used in the present invention is one or more selected from hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). From the perspective of easy availability of raw materials and favorable costs, it is preferred to use a dimethylsiloxane mixed ring body. More preferred is a mixture of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5).

[0088] The phenylcyclosiloxane used in the present invention is one or more selected from octaphenylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, a mixed ring body of methylphenyl and diphenyl (for example, a ring body having structures of formula (4) and (5) at the same time), and hydrolyzed oils thereof.

[0089] In one embodiment, the phenylcyclosiloxane used is octaphenylcyclotetrasiloxane, and the resulting methylphenyl silicone oil has the structural unit shown in the above formula (5).

[0090] In one embodiment, the phenylcyclosiloxane used is tetramethyltetraphenylcyclotetrasiloxane, and the resulting methylphenyl silicone oil has the structural unit represented by the above formula (4) as a repeating unit.

[0091] The end-capping agent used in the preparation method of the present invention is diphenyltetramethyldisiloxane or hexaphenyldisiloxane. In the embodiment using diphenyltetramethyldisiloxane as the end-capping agent, the obtained methylphenyl silicone oil has the end-capping group shown in formula (1). In the embodiment using hexaphenyldisiloxane as the end-capping agent, the obtained methylphenyl silicone oil has the end-capping group shown in formula (2).

[0092] In the preparation method of the present invention, the appropriate amount of dimethylcyclosiloxane and phenylcyclosiloxane can be selected according to the amount of the structural units represented by formula (3), (4) and (5) in the product.

[0093] In one embodiment, the amount of dimethylcyclosiloxane used is 15 to 100%, preferably 20 to 85%, relative to the total mass of dimethylcyclosiloxane and phenylcyclosiloxane.

[0094] In one embodiment, the amount of phenylcyclosiloxane used is 0-85%, preferably 15-80%, relative to the total mass of dimethylcyclosiloxane and phenylcyclosiloxane.

[0095] In one embodiment, the amount of the end-capping agent is 5-20% relative to the total mass of dimethylcyclosiloxane and phenylcyclosiloxane.

[0096] The catalyst used in the present invention is potassium hydroxide, which can be used directly or in the form of alkali gel. The amount of the catalyst used in terms of potassium is 20 to 200 ppm, preferably 30 to 150 ppm, and more preferably 50 to 100 ppm relative to the total weight of the reaction system.

[0097] Step (a) Dehydration

[0098] The preparation method of the present invention first dehydrates a mixture including dimethylcyclosiloxane, phenylcyclosiloxane, a capping agent and a catalyst. The purpose of dehydration is to reduce the water content of the system to avoid the formation of silanol groups, which affects the quality of silicone oil. Water can also reduce the reaction activity of the catalyst, thereby affecting the equilibrium polymerization reaction, which will lead to uneven molecular weight distribution and phenyl distribution.

[0099] In one embodiment, the dehydration is performed by one or a combination of two methods of distillation under reduced pressure or nitrogen bubbling.

[0100] Preferably, the relative vacuum degree during the reduced pressure distillation is -0.08 MPa to -0.1 MPa, the time of the reduced pressure distillation is preferably 0.5 to 5 hours, preferably 1 to 3 hours, and the temperature of the reduced pressure distillation is preferably 40 to 90°C.

[0101] In one embodiment, the temperature of the vacuum distillation is 40-70° C., preferably 50-60° C. In another embodiment, the temperature of the vacuum distillation is 80-90° C. In this embodiment, part of the dimethylcyclosiloxane is distilled off while dehydrating.

[0102] Preferably, nitrogen bubbling is performed by continuously passing nitrogen into the mixture, and the passing time is preferably 0.5 to 5 hours, preferably 1 to 3 hours, and the temperature during the passing of nitrogen is 20 to 40° C., such as room temperature.

[0103] Step (b) Equilibrium polymerization

[0104] In step (b), the dimethylcyclosiloxane and the phenylcyclosiloxane in the dehydrated mixture are subjected to a balanced polymerization reaction in the presence of a catalyst, and are subjected to an end-capping reaction with an end-capping agent, thereby obtaining methylphenyl silicone oil.

[0105] The commonly used method for preparing methylphenyl silicone oil is anion catalytic equilibrium polymerization, and the commonly used catalysts are potassium hydroxide and tetramethylammonium hydroxide. Tetramethylammonium hydroxide is generally used as a reaction catalyst in China. The advantages are low reaction temperature and no catalyst residue, but the disadvantage is that the synthesized silicone oil has a taste and is difficult to remove. In addition, for the preparation of triphenyl-terminated methylphenyl silicone oil, since the reaction belongs to a solid-liquid polymerization reaction, low temperature is not conducive to the balance of the reaction. Therefore, the present invention uses potassium hydroxide as a reaction catalyst, and it is more preferred to prepare potassium hydroxide into alkali glue for use, which can be dissolved in the system faster.

[0106] In one embodiment, the amount of potassium hydroxide used is 20 to 200 ppm, preferably 40 to 150 ppm, and more preferably 50 to 100 ppm, relative to the total weight of the reaction system. If the amount of catalyst used is too small, the reaction will be too slow or even non-reactive. If the amount of catalyst used is too large, the burden of subsequent treatment will be increased and the performance of the silicone oil will be adversely affected.

[0107] In one embodiment, the polymerization temperature is 150-190° C., preferably 170-180° C.; the polymerization time is preferably 2-20 hours, preferably 4-16 hours, and more preferably 6-18 hours.

[0108] Step (c) Catalyst Destruction

[0109] After the polymerization reaction is completed, an acidic neutralizer is added to the reaction system to deactivate the catalyst.

[0110] In one embodiment, the acidic neutralizer is at least one selected from phosphoric acid, silicon-based phosphate ester, acetic acid, and carbon dioxide, preferably silicon-based phosphate ester.

[0111] In the embodiment using carbon dioxide, carbon dioxide gas may be introduced into the reaction system for bubbling, so that the carbon dioxide and potassium hydroxide undergo an acid-base neutralization reaction to deactivate the catalyst.

[0112] In the embodiment using silicon-based phosphate, the silicon-based phosphate can be dissolved in dimethylcyclosiloxane (e.g., octamethylcyclotetrasiloxane) and then added to the reaction system. The mass concentration of silicon-based phosphate dissolved in dimethylcyclosiloxane is 3-15 mass %.

[0113] In one embodiment, the amount of the acidic neutralizer added is 5 to 20 times that of the catalyst by mass.

[0114] In one embodiment, the reaction system after the polymerization reaction is first cooled to 100-130° C., and then the acidic neutralizing agent is added to the reaction system.

[0115] Step (d) Take off the

[0116] After the activity of the catalyst is destroyed, the low-boiling point substances in the reaction system are removed.

[0117] Wherein, the low boiling point substance is one or more selected from diphenyltetramethyldisiloxane, dimethylcyclosiloxane, and methylphenylcyclosiloxane.

[0118] In one embodiment, the low boiling point substances in the reaction system are removed by subjecting the reaction system to reduced pressure distillation or short path distillation (molecular distillation).

[0119] Preferably, the pressure of the reduced pressure distillation is 100 Pa or less.

[0120] Preferably, the temperature of the deoxidation step is below 300° C., preferably below 280° C., for example, 150-300° C., preferably 200-280° C. By controlling the deoxidation temperature within the above range, the obtained methylphenyl silicone oil can be made odorless and colorless, thus having a wider range of uses.

[0121] Preparation of end-capping agent

[0122] In one embodiment, before step (a), a step of preparing a capping agent is further included.

[0123] Preparation of diphenyltetramethyldisiloxane

[0124] In the present invention, the steps of preparing diphenyltetramethyldisiloxane include: hydrolyzing phenyldimethylmonochlorosilane in an organic solvent A in the presence of water, and then separating and purifying the reaction product; the separation and purification includes stratifying the system after the hydrolysis reaction, and then washing the organic layer with water, neutralizing with alkali, dehydrating, removing the solvent and performing reduced pressure distillation operations.

[0125] Specifically, the organic solvent A is a non-polar organic solvent, preferably one or more selected from benzene, toluene, xylene, n-hexane, and cyclohexane, more preferably benzene, toluene, and xylene, and most preferably toluene. The purpose of carrying out the hydrolysis reaction of phenyldimethylchlorosilane in a non-polar organic solvent is to allow the phenyldimethylsilanol and diphenyltetramethyldisiloxane produced by the hydrolysis to be dissolved in the solvent, so as to facilitate the separation from the generated hydrochloric acid and the subsequent water washing and neutralization.

[0126] Specifically, the temperature of the hydrolysis reaction is 20 to 80°C, more preferably 40 to 60°C.

[0127] Specifically, after the hydrolysis reaction is completed, the organic layer is washed with deionized water to a pH of 6-7.

[0128] Specifically, after washing with water, the organic layer is neutralized with alkali to pH = 7 to 14, preferably pH = 8 to 9. The alkali used for alkali neutralization is one or more selected from organic alkalis and inorganic alkalis, the organic alkali is preferably tetramethylammonium hydroxide, and the inorganic alkali is preferably sodium hydroxide or potassium hydroxide.

[0129] Preferably, after neutralization with the base, the reaction system is heated to reflux of the solvent, and a condensation reaction is carried out in the presence of a base to remove the silanol groups. The reaction time is preferably 2 to 4 hours, and the generated water can be removed while refluxing.

[0130] Specifically, the solvent is removed by distillation under normal pressure or reduced pressure, and more preferably, distillation is first performed under normal pressure to remove part of the solvent, and then distillation is performed under reduced pressure to remove the remaining solvent. This combination of methods can better remove the solvent.

[0131] Preferably, after the solvent is removed, the product diphenyltetramethyldisiloxane is distilled out of the system by distillation under reduced pressure, thereby purifying the product.

[0132] Preparation of Hexaphenyldisiloxane

[0133] In the present invention, the steps of preparing hexaphenyldisiloxane include: dissolving triphenylsilanol in an organic solvent B, then carrying out a condensation reaction in the presence of an alkali catalyst under the condition of solvent reflux, and then separating and purifying the reaction product; the separation and purification includes cooling crystallization, filtering, washing with water and drying.

[0134] Specifically, organic solvent B is a polar organic solvent, preferably one or more selected from methanol, ethanol, acetone, butanone, methyl isobutyl ketone, more preferably acetone. Due to the solid crystallization of triphenylsilanol, it is soluble in polar organic solvents, so polar organic solvents are used. In addition, considering that the solubility of triphenylsilanol in ketone is higher, acetone is more preferably used as reaction solvent.

[0135] Specifically, the base catalyst is one or more selected from organic bases and inorganic bases. The organic base is preferably tetramethylammonium hydroxide, and the inorganic base is preferably sodium hydroxide or potassium hydroxide.

[0136] Specifically, the reaction temperature is the reflux temperature of the solvent, which is conducive to the condensation reaction.

[0137] Since triphenylsilanol has a large steric hindrance, it is preferred to control the reflux time (reaction time) to be more than 6 hours in order to obtain a higher yield of hexaphenyldisiloxane.

[0138] In the case of using acetone, since the solubility of hexaphenyldisiloxane in acetone is relatively low, after the reaction is completed, the product can be separated and purified by cooling, crystallizing, filtering, washing with water and drying to obtain white crystals with a melting point greater than 220°C.

[0139] The present invention also correspondingly relates to the methylphenyl silicone oil prepared by the method of the present invention.

[0140] <Properties of methylphenyl silicone oil>

[0141] The refractive index of the methylphenyl silicone oil of the present invention is 1.49 or more, preferably 1.5 or more.

[0142] The viscosity of the methylphenyl silicone oil of the present invention is 100-1200 mm² / s. More specifically, the viscosity of the phenyldimethyl terminated methylphenyl silicone oil of the present invention is 100-200 mm² / s, more preferably 100-150 mm² / s; the viscosity of the triphenyl terminated methylphenyl silicone oil of the present invention is 400-1200 mm² / s, preferably 500-1000 mm² / s.

[0143] The flash point of the methylphenyl silicone oil of the present invention is above 300° C., preferably above 310° C. More specifically, the viscosity of the phenyldimethyl terminated methylphenyl silicone oil of the present invention is above 300° C., preferably above 310° C., and the viscosity of the triphenyl terminated methylphenyl silicone oil of the present invention is above 340° C., preferably above 350° C. Example

[0144] The present invention is further described by enumerating specific implementation cases below. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content recorded in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the present invention equally.

[0145] The dimethylcyclosiloxane used in the following examples is a DMC mixture, the main components of which are octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, mainly containing octamethylcyclotetrasiloxane.

[0146] Preparation Example 1: Preparation of diphenyltetramethyldisiloxane

[0147] Place 170.7 grams of phenyldimethylchlorosilane (purity greater than 99%) and 256 grams of toluene in a dropping funnel, add 207 grams of deionized water to a four-necked flask, heat to 30°C, slowly drop the material in the dropping funnel into the four-necked flask, control the temperature at about 50°C, stir for 30 minutes after the addition is complete, let it stand for stratification, remove the hydrochloric acid layer, wash the organic layer with deionized water until it is close to neutral, then add sodium hydroxide to adjust to PH=8, heat to toluene reflux, and remove water until no more water is produced. Then, evaporate part of the toluene under normal pressure, and finally evaporate the residual toluene at a temperature not exceeding 150°C. The material in the flask is simply distilled to obtain 132 grams of colorless transparent liquid with a refractive index of 1.52 and a purity of 99.54% as tested by gas chromatography.

[0148] Preparation Example 2: Preparation of hexaphenyldisiloxane

[0149] 200 g of triphenylsilanol, 320 g of acetone and 0.2 g of sodium hydroxide were placed in a four-necked flask, heated to reflux and maintained for 10 hours, then cooled, filtered, washed with water and dried to obtain hexaphenyldisiloxane. The melting point was tested to be 225°C.

[0150] Example 1

[0151] 207.2 g of dimethylcyclosiloxane (DMC), 51.6 g of diphenyltetramethyldisiloxane, 237.6 g of octaphenylcyclotetrasiloxane and 0.5 g of potassium hydroxide alkali gel catalyst with a mass concentration of 5wt% were added to a four-necked flask, and the temperature was slowly raised to 50-60°C. The vacuum was adjusted to -0.09MPa for dehydration, and the dehydration time was 2 hours. Then the temperature was raised to 170-180°C for polymerization. After the polymerization was balanced for 6 hours, the temperature was lowered to 120°C, and 0.3 g of trimethylsilyl phosphate was dissolved in 5 g of octamethylcyclotetrasiloxane and added to the flask. After stirring for 1 hour, the vacuum was evacuated until the pressure reached below 100Pa, and the temperature was raised to 280°C for dehydration until there was no more effluent. Then the temperature was lowered and filtered to obtain colorless and transparent phenyldimethyl-terminated methylphenyl silicone oil with a viscosity of 142mm² / s, a refractive index of 1.4956, and a flash point of 318°C.

[0152] Example 2

[0153] 118.4 g of dimethylcyclosiloxane, 44.4 g of diphenyltetramethyldisiloxane, 272 g of tetramethyltetraphenylcyclotetrasiloxane and 0.5 g of 5% potassium hydroxide alkali gel catalyst were added to a four-necked flask, and the temperature was slowly raised to 50-60°C. The vacuum was adjusted to -0.09 MPa for dehydration, and the dehydration time was 2 hours. Then the temperature was raised to 170-180°C for polymerization. After the polymerization was balanced for 6 hours, the temperature was lowered to 120°C, and 0.3 g of trimethylsilyl phosphate was dissolved in 5 g of octamethylcyclotetrasiloxane and added to the four-necked flask. After stirring for 1 hour, the vacuum was evacuated until the pressure reached below 100 Pa, and the temperature was raised to 280°C for dehydration until there was no more effluent. After cooling and filtering, a colorless and transparent phenyldimethyl-terminated methylphenyl silicone oil was obtained, with a viscosity of 125 mm² / s, a refractive index of 1.51, and a flash point of 325°C.

[0154] Example 3

[0155] 571.4 g of dimethylcyclosiloxane, 143 g of hexaphenyldisiloxane, 285.6 g of octaphenylcyclotetrasiloxane and 2 g of potassium hydroxide alkali gel catalyst with a mass concentration of 5% were added to a four-necked flask, and the temperature was slowly raised to 50-60°C. The vacuum was adjusted to -0.09 MPa for dehydration, and the dehydration time was 2 hours. Then the temperature was raised to 170-180°C for polymerization. After the polymerization was balanced for 12 hours, the temperature was lowered to 120°C, and 1.2 g of trimethylsilyl phosphate was dissolved in 10 g of octamethylcyclotetrasiloxane and added to the four-necked flask. After stirring for 1 hour, the vacuum was evacuated to below 100 Pa, and the temperature was raised to 280°C for dehydration until there was no more effluent. After cooling and filtering, a colorless and transparent triphenyl-terminated methylphenyl silicone oil was obtained with a viscosity of 500 mm² / s, a refractive index of 1.494, and a flash point of 342°C.

[0156] Example 4

[0157] 529.4 g of dimethylcyclosiloxane, 117.7 g of hexaphenyldisiloxane, 352.9 g of octaphenylcyclotetrasiloxane and 2 g of potassium hydroxide alkali gel catalyst with a mass concentration of 5% were added to a four-necked flask, and the temperature was slowly raised to 50-60°C. The vacuum was adjusted to -0.09 MPa for dehydration, and the dehydration time was 2 hours. Then the temperature was raised to 170-180°C for polymerization. After the polymerization was balanced for 12 hours, the temperature was lowered to 120°C, and 1.2 g of trimethylsilyl phosphate was dissolved in 10 g of octamethylcyclotetrasiloxane and added to the four-necked flask. After stirring for 1 hour, the vacuum was evacuated until the pressure reached below 100 Pa, and the temperature was raised to 280°C for dehydration until there was no more effluent. After cooling and filtering, a colorless and transparent triphenyl-terminated methylphenyl silicone oil was obtained with a viscosity of 990 mm² / s, a refractive index of 1.5026, and a flash point of 356°C.

[0158] Industrial Applicability

[0159] The methylphenyl silicone oil of the present invention can be widely used in the fields of lubrication, insulation, demoulding, damping, shockproof and dustproof.

Claims

1. A methylphenyl silicone oil, characterized in that: The methylphenyl silicone oil has a structure shown in the following formula (II): Formula (II), Wherein, x, y and z represent the molar ratio of the three structural units, x+y+z=1, x is 0.65~0.9, y is 0~0.3, and z is 0.1~0.

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2. The method for preparing methylphenyl silicone oil according to claim 1, characterized in that: The following steps are involved: (a) Dehydration: Dehydrating a mixture comprising dimethylcyclosiloxane, phenylcyclosiloxane, a capping agent and a catalyst, (b) Equilibrium polymerization: the dehydrated mixture is subjected to polymerization reaction. (c) Catalyst destruction: adding an acidic neutralizing agent to destroy the activity of the catalyst, and (d) Removal of low boiling point substances from the reaction system; Wherein, the phenylcyclosiloxane is one or more selected from octaphenylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, a mixed ring of methylphenyl and diphenyl, and their hydrolyzed oils; The end-capping agent is hexaphenyldisiloxane; The catalyst is potassium hydroxide; The acidic neutralizer is at least one selected from phosphoric acid, silicon-based phosphate ester, acetic acid, and carbon dioxide.

3. The preparation method according to claim 2, characterized in that: The dehydration in step (a) is carried out by one or a combination of reduced pressure distillation or nitrogen bubbling; wherein the temperature during the reduced pressure distillation is 40-90° C., and the relative vacuum degree is -0.08 MPa-0.1 MPa; and the mass amount of the end-capping agent is 5-20% relative to the total mass of the dimethylcyclosiloxane and the phenylcyclosiloxane.

4. The preparation method according to claim 2, characterized in that: In step (b), the polymerization reaction temperature is 150-190° C.; the amount of the catalyst used, calculated as potassium, is 20-200 ppm relative to the total weight of the reaction system.

5. The preparation method according to claim 2, characterized in that: In step (c), the reaction system is first cooled to 100-130° C., and then the acidic neutralizer is added to the reaction system; the amount of the acidic neutralizer added is 5-20 times that of the catalyst by mass.

6. The preparation method according to claim 2, characterized in that: In step (d), low boiling point substances in the reaction system are removed by vacuum distillation or short-path distillation, the pressure of the vacuum distillation is below 100 Pa, and the temperature is 150-300° C.; the low boiling point substances are one or two selected from dimethylcyclosiloxane and methylphenylcyclosiloxane.

7. The preparation method according to claim 2, characterized in that: Also included is the step of preparing hexaphenyldisiloxane as a capping agent, The steps of preparing hexaphenyldisiloxane include: dissolving triphenylsilanol in an organic solvent B, then carrying out a condensation reaction in the presence of an alkali catalyst and under the condition of solvent reflux, and then separating and purifying the reaction product; the separation and purification includes cooling crystallization, filtering, washing with water and drying.

8. The preparation method according to claim 7, characterized in that: The organic solvent B is a polar organic solvent; The base catalyst is one or more selected from organic bases and inorganic bases.

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